Field of the Invention
This invention relates to a medical material, a method for the production thereof, and a medical apparatus which stably exhibits high biocompatiblility and excellent safety for a long time.
In recent years, artificial internal organs such as artificial kidneys, artificial lungs, and blood separating devices have been produced and put to use. The materials of which these artificial internal organs are formed are required to possess excellent biocompatiblility. Use of an artificial internal organ destitute of biocompatibility is highly dangerous because the contact of the material thereof with blood or vital tissue has the possibility of injuring hemocytes in the blood and inducing the formation of plasma protein and thrombosis. For the impartation of biocompatibility to the materials forming artificial internal organs, therefore, various methods for reformation have been heretofore proposed.
Particularly the practice of effecting graft polymerization by the use of a macromer has been recently in vogue. The formation of a graft copolymer, for example, has been attained by copolymerizing the macromer of a methacrylic ester with 2-hydroxyethyl methacrylate. It has been known that this graft copolymer has a better antithrombic property than countertype homopolymers and random copolymers ("Medical Materials and Organism," page 37 and pages 287 to 289, compiled by Yukio Imanish et al. and published by Kodansha Scientific K.K., 1982). In the graft copolymer produced by this polymerization of a macromer with other monomer, the graft chain is formed not only on the surface of the polymer but in the interior of the polymer. The graft copolymer, therefore, has the problem of introducing a change in the internal quality of the polymer.
The method for enhancing the biocompatibility of a medical material by physically coating this material on the surface with an oil-soluble vitamin has been known to the art (U.S. Pat. No. 4,588,407, for example). The medical material having the surface thereof coated with the oil-soluble vitamin brings about a secondary effect sparingly on organisms and avoids causing any transient decrease in leukocyte. The coating of an oil-soluble vitamin deposited only physically on the surface of the material, however, exhibits to the substrate material such a weak binding force as to entail possible migration of the vitamin into the blood.
This invention, therefore, has as an object thereof the provision of a novel medical material and a method for the production thereof.
Another object of this invention is to provide a medical material which exhibits high biocompatibility stably for a long time and which also excels in safety.